im a bit fanatical in this area as being a smoker with pets i clean everything inside and out once a month.

purchase a can of compressed air some q-tips screen wipes and 100ml or so of isopropanol alcohol(get this from chemist) and a small paint brush.

wipe screen/casing and keyboard/mouse daily with wipes. clean ball of mouse and rollers once a month with isopropanol and q-tips.

open case once a month and remove all case fans and clean the blades with isopropanol and q-tips.do the same for the cpu (only the fan)

use the brush to dust down the motherboard and cards and then blow dust off all cards and motherboard and cpu heatsink with can of compressed air.remove graphics card fan and clean also as above.

carefully hoover out settled dust and gunk from bottom of case then wipe inside of case with wipes.

my tip is to use a piece of material cut from a pair of tights and attach it to case fans with an elastic band.this keeps most dust and gunk from entering and makes clean up time easier.wash tights (filters) and replace.

Normal levels of dust do very little harm in a pc except when it gets into the heatsink matrix or forms a thick layer on fan blades. Unless your pc is in a very dusty area, then I don't think cleaning the inside need be done more than once a year, and then unless the dust layer is thick, use something like an artists brush to loosen dust from fan blades and the heatsink matrix, and a compressed air can to blow out what you can't reach. Dusting the circuit boards and using a vacuum cleaner can be done, but you need to weigh up the benefits against the small but real risk of static electrical damage.

If you have temperature sensing software such as MotherBoard Monitor MBM5 from click here, then you will know when cleaning is due because the temperatures will start to rise.

As Gandalf <|:-)> has already commented, in another thread, i have a pc with fur balls.

Glad to see i'm not the only one. It would seem the worst combo is smoking and pet hair, guess the smoke makes the hair especially sticky.

Huggyg71 fianlly gave me an answer to a question i have had for ages but never thought worth asking- what to use as a filter for a pc- old tights....Just got to convince girlfriend to let me cut her tights up......